On Mon 2012-11-26T18:30:09 +0000, Poul-Henning Kamp hath writ: > Uhm, they run PTP, so what ?
That doesn't quite seem to be the case. The paper is at http://static.googleusercontent.com/external_content/untrusted_dlcp/research.google.com/en//archive/spanner-osdi2012.pdf In that is The underlying time references used by TrueTime are GPS and atomic clocks. TrueTime uses two forms of time reference because they have different failure modes. GPS reference-source vulnerabilities include antenna and receiver failures, local radio interference, correlated failures (e.g., design faults such as incorrect leapsecond handling and spoofing), and GPS system outages. Atomic clocks can fail in ways uncorrelated to GPS and each other, and over long periods of time can drift significantly due to frequency error. It seems to indicate that the "leap smear" is one of the features implemented within this scheme. -- Steve Allen <[email protected]> WGS-84 (GPS) UCO/Lick Observatory--ISB Natural Sciences II, Room 165 Lat +36.99855 1156 High Street Voice: +1 831 459 3046 Lng -122.06015 Santa Cruz, CA 95064 http://www.ucolick.org/~sla/ Hgt +250 m _______________________________________________ LEAPSECS mailing list [email protected] http://six.pairlist.net/mailman/listinfo/leapsecs
